Vehicles can employ headlamps which comprise light sources for emitting blue light beam, onto yellow fluorescent layers. The yellow fluorescent layer comprises fluorescent powders which are triggered by the blue light beam to form yellow light beam. The blue light beam is then mixed with the yellow light beam to form white light beam for illumination purposes.
However, the fluorescing powders may not been distributed in the yellow fluorescent layer uniformly. Thus, different parts of the yellow fluorescent layer are not evenly triggered by the blue light beam, thus causing the laser beam travelling out of the headlamp to become slightly blue or slightly yellow.